code: def test_positions(self, x, y):
      p = Plot(x, y).add(Bars()).plot()
      ax = p._figure.axes[0]
      paths = ax.collections[0].get_paths()
      assert len(paths) == len(x)
      for i, path in enumerate(paths):
          verts = path.vertices
          assert verts[0, 0] == pytest.approx(x[i] - 0.5)
          assert verts[1, 0] == pytest.approx(x[i] + 0.5)
          assert verts[0, 1] == 0
          assert verts[3, 1] == y[i]
  
imports: import numpy
  import pandas
  from matplotlib.colors import to_rgba, to_rgba_array
  import pytest
  from numpy.testing import assert_array_equal
  from seaborn._core.plot import Plot
  from seaborn._marks.bar import Bar, Bars
label_desc: Use image node_id 4 for calling the TestBars obj's underlying member method code with example usage: obj.test_positions(x, y) without return types